http://www.diva-portal.org This is the published version of a paper published in Metabolomics. Citation for the original published paper (version of record): Papazian, S., Girdwood, T., Wessels, B A., Poelman, E H., Dicke, M. et al. (2019) Leaf metabolic signatures induced by real and simulated herbivory in black mustard (Brassica nigra) Metabolomics, 15(10): 130 https://doi.org/10.1007/s11306-019-1592-4 Access to the published version may require subscription. N.B. When citing this work, cite the original published paper. Permanent link to this version: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-164033 Metabolomics (2019) 15:130 https://doi.org/10.1007/s11306-019-1592-4 ORIGINAL ARTICLE Leaf metabolic signatures induced by real and simulated herbivory in black mustard (Brassica nigra) Stefano Papazian1 · Tristan Girdwood1 · Bernard A. Wessels1 · Erik H. Poelman2 · Marcel Dicke2 · Thomas Moritz3 · Benedicte R. Albrectsen1 Received: 30 April 2019 / Accepted: 12 September 2019 © The Author(s) 2019 Abstract Introduction The oxylipin methyl jasmonate (MeJA) is a plant hormone active in response signalling and defence against herbivores. Although MeJA is applied experimentally to mimic herbivory and induce plant defences, its downstream efects on the plant metabolome are largely uncharacterized, especially in the context of primary growth and tissue-specifcity of the response. Objectives We investigated the efects of MeJA-simulated and real caterpillar herbivory on the foliar metabolome of the wild plant Brassica nigra and monitored the herbivore-induced responses in relation to leaf ontogeny. Methods As single or multiple herbivory treatments, MeJA- and mock-sprayed plants were consecutively exposed to cater- pillars or left untreated. Gas chromatography (GC) and liquid chromatography (LC) time-of-fight mass-spectrometry (TOF- MS) were combined to analyse foliar compounds, including central primary and specialized defensive plant metabolites. Results Plant responses were stronger in young leaves, which simultaneously induced higher chlorophyll levels. Both MeJA and caterpillar herbivory induced similar, but not identical, accumulation of tricarboxylic acids (TCAs), glucosinolates (GSLs) and phenylpropanoids (PPs), but only caterpillar feeding led to depletion of amino acids. MeJA followed by cater- pillars caused higher induction of defence compounds, including a three-fold increase in the major defence compound allyl- GSL (sinigrin). When feeding on MeJA-treated plants, caterpillars gained less weight indicative of the reduced host-plant quality and enhanced resistance. Conclusions The metabolomics approach showed that plant responses induced by herbivory extend beyond the regulation of defence metabolism and are tightly modulated throughout leaf development. This leads to a new understanding of the plant metabolic potential that can be exploited for future plant protection strategies. Keywords Metabolomics · Methyl jasmonate · Brassica nigra · Growth-defence allocation · Priming · Herbivore-induced responses · Leaf ontogeny · Glucosinolates Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s1130 6-019-1592-4) contains supplementary material, which is available to authorized users. * Benedicte R. Albrectsen Thomas Moritz [email protected] [email protected] Stefano Papazian 1 Department of Plant Physiology, Umeå University (Umeå [email protected] Plant Science Centre), 90187 Umeå, Sweden Tristan Girdwood 2 Laboratory of Entomology, Wageningen University, [email protected] 6700 AA Wageningen, The Netherlands Bernard A. Wessels 3 Department of Forest Genetic and Plant Physiology, Swedish [email protected] University of Agricultural Sciences (Umeå Plant Science Erik H. Poelman Centre), 90187 Umeå, Sweden [email protected] Marcel Dicke [email protected] Vol.:(0123456789)1 3 130 Page 2 of 16 S. Papazian et al. Abbreviations and organs (Lortzing and Steppuhn 2016). JA signals can ET Ethylene travel along the phloem leading to systemic responses GSL Glucosinolate (Glauser et al. 2008; Mousavi et al. 2013), while the ester PP Phenylpropanoid derivative methyl-JA (MeJA), as a volatile cue, can transfer GC Gas chromatography resistance responses through air to remote plant parts and IS Internal standard even between neighbouring plants (Farmer and Ryan 1990; JA Jasmonic acid Wasternack and Song 2017). Exposure to either JA or MeJA LC Liquid chromatography typically elicits the production of plant defence metabolites, MeJA Methyl jasmonate e.g. GSLs (van Dam and Oomen 2008; Fritz et al. 2010; SA Salicylic acid Zang et al. 2015; Yi et al. 2016). For these reasons, JA and TOF-MS Time-of-fight mass spectrometry MeJA are frequently applied to plants to simulate herbivory TCA​ Tricarboxylic acid experimentally and to enhance, or prime, plant resistance (Sampedro et al. 2011; Balmer et al. 2015; Lortzing and Steppuhn 2016). 1 Introduction Plants continuously adjust their metabolism to account for future growth and ecological ftness opportunities (McKey Plants are constitutively protected against herbivores by 1974; Heil and Baldwin 2002; McCall and Fordyce 2010; several mechanisms including physical barriers (e.g. tri- Meldau et al. 2012). Accordingly, in response to damage, chomes and thorns) and chemical defences (D’Auria and chemical defences are hypothesized to be induced and dis- Gershenzon 2005; Milkowski and Strack 2010; Onkokesung tributed following developmental needs, with higher invest- et al. 2014). Upon damage, defences are further induced ments in protecting young tissues compared to older ones by rapid metabolic reconfgurations (Karban 2011; Meldau (Brown et al. 2003; Traw and Feeny 2008; Havko et al. 2016; et al. 2012). The plant metabolome is highly interconnected Ochoa-López et al. 2015; de Vries et al. 2017; Chrétien through enzymatic reactions of which some are responsible et al. 2018). Because leaf metabolism changes throughout for the synthesis of specialized defence metabolites, such as its development—e.g. with young leaves starting as sinks to phenylpropanoids (PPs) and glucosinolates (GSLs, Halkier later become sources of photosynthate during maturation, and Gershenzon 2006; Morrisey 2009). Specialized (or ‘sec- leaf ontogeny may infuence the plant herbivore-induced ondary’) biosynthetic metabolic pathways are taxon-specifc metabolic responses (Pantin et al. 2012; Townsley and Sinha and evolved from the central (or ‘primary’) metabolism 2012; Quintero et al. 2014; Ochoa-López et al. 2015; Barton (Firn and Jones 2009; Weng 2014; Moghe and Last 2015), and Boege 2017; Brütting et al. 2017). Thus, a combina- which is related to growth, photosynthesis, and nitrogen tion of a plant’s external and internal signals may eventually assimilation, but which is also responsible for the produc- lead to a metabolic reorganization cascade that strengthens tion of precursors of specialised compounds. Most defence resistance against herbivores, but which can also afect metabolites further depend on conjugated sugar moieties for plant growth and central energy metabolism (Schwachtje stability, translocation, and storage inside the plant’s cel- and Baldwin 2008; Zhou et al. 2015; Papazian et al. 2016, lular compartments (Rask et al. 2000; Gachon et al. 2005; Huang et al. 2017; Machado et al. 2017; Guo et al. 2018). Le Roy et al. 2016). It is consequently well accepted that Metabolomics can provide detailed information about the herbivore-induced responses of plants not only result in complexity and dynamics of plant metabolism and it may de-novo synthesis of defence compounds, but also depend detect minute responses to abiotic or biotic stress factors on the central metabolism (Schwachtje and Baldwin 2008; (Jansen et al. 2009; Khaling et al. 2015; Maag et al. 2015; Zhou et al. 2015). Papazian et al. 2016; Peng et al. 2016; Ponzio et al. 2017). Plant hormones are signalling chemicals that are present Here, we applied metabolomics to carry out an in-depth in small concentrations, e.g., auxin, cytokinins, ethylene analysis of the wild black mustard plant (Brassica nigra) (ET), salicylic acid (SA), and jasmonic acid (JA). They foliar metabolome in response to herbivory. Our focus was control plant growth metabolism and coordinate and inte- to evaluate the efects of MeJA-simulated herbivory and cat- grate the metabolic crosstalk processes that direct resources erpillar feeding by the specialist herbivore Pieris brassicae between developmental and protective needs (Erb et al. on the metabolic response of B. nigra. The experimental 2012; Huot et al. 2014). JA and its derivatives belong to a design included plants exposed to four kinds of treatment: class of oxylipins, synthesized from the octadecanoid path- untreated controls (C), herbivory simulated with MeJA (M), way, that are particularly induced by chewing herbivores real herbivory by caterpillars (P), and pre-treatment with (Farmer and Ryan 1992; Huang et al. 2017; Wasternack and MeJA followed by caterpillar feeding (MP). The efects of Song 2017). Upon herbivore attack, JA accumulates intra- the treatments were evaluated in leaves of diferent ages cellularly and initiates signal transductions across tissues to include both mature and young leaves. Specifcally, the 1 3 Leaf metabolic signatures induced by real and simulated herbivory in black mustard (Brassica… Page 3 of 16 130 research questions set for this study were: (1) How does the a model system of chemical ecological interactions (Blatt MeJA